I recently completed an L83/6L80 swap to an L86/8L90 swap in a 2014 Silverado. The donor vehicle was a 2017 Silverado. Only problem I'm having is when I shift into drive, trans stays in 4th gear all the time. Also getting DTC's P0700 and P2534/P2535. I read somewhere that someone with a similar problem used a relay to control ignition wiring with ECM/TCM. Anyone familiar with this or maybe point me in the right direction? E92 & T87A